The invention relates to a fan, and particularly to a composite fan that has guide vanes to substitute for brackets of driving devices.
Refer to FIG. 1 for a conventional radiation air fan that includes a frame 31 housing a plurality of rotary vanes 32. The rotary vanes 32 are coupled radially on a hub 33 which is mounted on a driving device 34. The driving device 34 is fixedly located in the frame 31 through a bracket 35. When the driving device 34 rotates, it drives the hub 33 and the rotary vanes 32 to rotate and generate airflow. On the air outlet side of the rotary vanes 32, there is a plurality of guide vanes 36 to channel the airflow generated by the rotary vanes 32 to boost airflow volume and air pressure.
In the conventional structure set forth above, the bracket 35 merely serves to support the driving device 34. It takes a lot of space and increases the size of the radiation fan. Moreover, the bracket 35 disrupts the airflow generated by the rotary vanes 32. As a result, heat dissipation performance of the air fan suffers.
Refer to FIG. 2 for a conventional composite fan. It has two sets of rotary vanes 41 and 42 to match one set of guide vanes 43. Airflow generated by the first set of rotary vanes 41 is channeled by the guide vanes 43, and the other set of rotary vanes 42 rotates in the reverse direction to boost the airflow and heat dissipation efficiency of the air fan.
However, the composite structure mentioned above multiplies the disadvantages of the conventional air fans. In addition, with two sets of rotary vanes 41 and 42 driven respectively by separated driving devices 44 and 45; two brackets 46 and 47 are needed to support the driving devices 44 and 45. The size of the air fan increases significantly. This is against the prevailing trend that demands slim and light electronic devices.
In view of the aforesaid disadvantages, the primary object of the invention is to provide a composite fan that includes first guide vanes on the air outlet side of the first rotary vanes and second guide vanes on the air inlet side of the second rotary vanes to correspond to and couple with each other to form continuous curved surfaces. The first guide vanes and the second guide vanes are connected respectively in a radial manner to a first support section and a second support section that hold the driving devices to drive the first rotary vanes and the second rotary vanes.
In order to achieve the foregoing object, the composite fan of the invention consists of a first fan and a second fan. The first fan has a plurality of first rotary vanes and a plurality of first guide vanes located on the air outlet side of the first rotary vanes. The first guide vanes are coupled radially to a first support section that houses a first driving device. The first driving device drives the first rotary vanes to rotate and generate airflow.
The second fan has a plurality of second rotary vanes and a plurality of second guide vanes located on the air inlet side of the second rotary vanes. The second guide vanes are coupled radially to a second support section that houses a second driving device. The second driving device drives the second rotary vanes to rotate and generate airflow. The first rotary vanes and the second rotary vanes rotate in opposite directions to generate greater heat dissipation.
The main technical feature of the invention is that the second guide vanes corresponded to the first guide vanes in such a manner that each of the first guide vanes and each of the second guide vanes may be coupled to form a continuous curved surface. Thus when the first driving device drives the first rotary vanes to rotate and generate airflow, the airflow is channeled through the first and the second guide vanes to form increased airflow volume and air pressure. The boosted airflow is transferred to the second rotary vanes driven by the second driving device to form an even stronger airflow to be output.
The continuous curved surface formed by coupling the first guide vanes and the second guide vanes requires a matching design on the shape and structure of the first rotary vanes at the upstream location to increase output air pressure.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.